"Arkansas regulators are expected Tuesday to order the closure of some underground storage facilities that natural-gas drillers use to dispose of contaminated water because of concerns they are causing earthquakes.

The ban would only affect part of the state and wouldn't stop drilling in the Fayetteville Shale gas field there. But it highlights how water issues—including the disposal of waste tied to the controversial hydraulic fracturing process—have emerged as a major challenge for the oil and gas industry across the U.S."